Four Cleveland police officers' jobs were saved by body camera footage last week – but one had to be saved by his bulletproof vest first.

In a sign that body cameras may not just be a tool to expose police wrongdoing, footage from March was made public last week a day after a grand jury ruled that the officers' use of force was justified.

The rapid expansion of police body cameras around the country has occurred in a climate of heightened scrutiny of how and when police officers use lethal force – spurred by a spate of controversial deaths at police hands since protests broke out in Ferguson, Mo., over a year ago. Public trust in police is at its lowest point in decades.

Organizations from the Police Executive Research Forum to the American Civil Liberties Union argue that body cameras can increase transparency and accountability in police departments, ensuring that officers act within the letter of law and that, when they don’t, there’s documented evidence available to help try and punish them.

But the incident in Cleveland points to an added benefit: The notion that body camera footage could help exonerate police officers of crimes and improve their reputation in the eyes of the community.

"This is at least one case that supports the benefits of the police use of body cameras from a law enforcement standpoint," says Tod Burke, a professor of criminal justice at Radford University in Virginia.

'I know you shot me, but I’m not going to shoot you'

The dramatic footage from the March 11 incident shows the Cleveland patrol officers climbing the stairs to Theodore Johnson’s apartment. When one of the patrolmen, David Muniz, turns a corner, Mr. Johnson opens fire.

"I’ve been hit!" Officer Muniz shouts in the video.

In another video recorded by Muniz’s body camera, he and the other patrolmen plead with Johnson to put his gun down. Johnson is pleading with the officers to kill him.

Another officer can be heard telling Johnson to "put the gun down and we’ll get you all the help you need."

"I know you shot me, but I’m not going to shoot you," says Muniz, who is standing just a few feet from Johnson.

Johnson still refuses to drop the gun, which he is holding at his side.

A few seconds later he raises the gun, and the officers open fire.

A grand jury determined last week that the four patrolmen were justified in using lethal force against Johnson. They had gone to Johnson’s home that night after his wife went to a police station and reported that Johnson had threatened to kill both her and their landlady.

While there never seemed to be the kind of public outcry following Johnson's shooting that followed other recent police shootings, the Cleveland Police Department has endured a difficult 12 months.

Last November, the shooting of 12-year-old Tamir Rice sparked a national outrage that was only compounded when a judge found another Cleveland officer not guilty of murder for his role in the 2012 shooting of two unarmed black civilians. In May, the Cleveland Police Department entered into a consent decree with the United States Department of Justice after a federal report detailed "a pattern or practice of unreasonable and unnecessary use of force" and "the employment of poor and dangerous tactics that place officers in situations where avoidable force become inevitable."

With the reputation of Cleveland police so damaged, the release of the video could help prevent any deepening distrust of police, instead showing that the officers went "above and beyond" their duty in the situation, says Professor Burke, who is a former Maryland police officer.

"It was a horrible situation that obviously had deadly consequences, but at least we don’t have to be at this point questioning whether the officer was making up a story," says Burke.

Body cameras and better policing

The release of the video also comes as new questions are being raised as to when, and how, police body camera footage gets released to the public.

It took a lawsuit from three media organizations to unseal the dashboard camera footage of a 2013 police shooting outside Los Angeles, and the footage only became public earlier this year. And last week, the same day the Cleveland footage was released, The Washington Post published a report detailing that, of the 49 police shootings recorded by a body camera since January that the paper analyzed (they examined 760 such shootings in that time period), just 21 have been publicly released. And in many of those cases the officers involved were allowed to review the footage before it was released.

This debate is the "enduring challenge" of police body cameras, says Frederic Reamer, a professor in the School of Social Work at Rhode Island College in Providence.

"An essential element of that challenge is trying to construct guidelines and policies that provide a reasonable balance of privacy protection and public access, and that’s complicated," says Professor Reamer. "One of the challenges living in a democracy – and I should add I think it’s a challenge we ought to celebrate – is we have to take on these very difficult dilemmas that involved competing duties."

Early returns suggest that body cameras make both police officers and the public behave better. An interim report from the President’s Task Force on 21st Century Policing, released in March, cited a 12-month study that found "highly suggestive [results] that the use of BWCs [body-worn cameras] by the police can significantly reduce both officer use of force and complaints against officers."

"They found that the officers wearing the cameras had 87.5 percent fewer incidents of use of force and 59 percent fewer complaints than the officers not wearing the cameras," the Task Force added.

Burke thinks it’s still to early to say if body cameras will have a long-term positive effect on law enforcement, however. "Let’s do a long-term analysis, see where it’s been beneficial to law enforcement and community, and then let’s take a step back and see what we can improve."

In the meantime, he thinks the video released in Cleveland last week can not only help improve the embattled department’s image in the community, but can also give the American public hard video evidence of police work done right.

"Most times the officer is doing the right thing, and most times we only hear about it when they don’t," he says. "The nice thing about this case is it shows things being done right, and it was documented as such."